Process for gaining pure, tarfree sulphur from used gas-purifying mass



'KALMAN sZbMBATHY, orkAKosrA oTA; HUNG RY; AssreNoR or ONE-THIRD TO PAUL gsoHMI z Annfonn-rmnniro DOKTQR' ORNELLKELL;B0TH or DORTMUND, GER- fMANY j 1; I

' incense rumma ems meimesmam1 0M Usnn' GAS-PURIFYING Mass I ll'o Drawing. onl iiled January 21, "1928, Serial No. 248,575, and in Germany January 22, 1 92 Z;

This invention is a iioiiel process forrec'ov I ering pure tar-free 'sulphurffrom spent gas;

impo sibl to recover; byli eansjof a simple process the sulphur contained in used; or spent gasgpurifyingumaterial V and the like in I I-p1 1 I "and, si ce thesulplniii eccivered by the proc esses' was impure. flThe sulphunheretofore recovered from"spentgasepurifying material has jmoreo'ver, been so contaminated With tar that it has been necessary to sublimatethe Some years 'prev1"ous, a w process was develbpedIyvhereby'sulphur, 1-. e. crude." sulphur yerynearly pure couldfbelrecovered' in 1a finely fdi vided"or ven-fcolloidal' condi- V tion, by ,treating, sulphur with quick lime; KCaOh pend" sodium-sul hate1 (Na2SO4);

i ereb'y f sulphate g ee, calcium 2 QaSOQv and 7115fskidiuin polysulphidey .Nas V f. ;i., Ness ;V ta ined.- ,After filterr I I I I diuJn-polysulphide and ,sodium-thiosulphate ng fronithe mixture s0- and '.-upon intrQductiong of gsulphurous Jacid (SQ [sulphur yvas diilmahios lphatei This process has howeyer not been. -'e1n- "ployed lfor treating II I and presumably could not be'utiliz ed for this I purpose' owii gto' the contamination of the gas-purifying materi'alkwi-th t'ar, and for the same reason that "pure sulphur could'fnot be;

-gas-purifying material;

recovered by this processthe otherw ast' products, such as cyanogen and J IhOdLHldE combinations 'cont'ain'edin the-gas-purifying material could not gbe' recovered. I

' bonateforalka-linisulp'hates, but also that byico'rresponding:development-of the proc- .ess. the present cyanogen andfrhodanide'combinations could berecovered, sothat even or" particularly a tarfree condition, h therto employed, processes have been too ,jcircunistantialfl and unejconomic al, fparti c ul'arly finjjyiew ofthefilow' price of sulphur tarfand other insolublesubstances over to the deposit We'r While he I I esentjwas recovered a's such;indrycondition. i

the base of the gas-purifying material be} came suitable for re-employment. My present process is ground raw boiledwith I (Ca(OH and simultaneously or subsephate; (NagSOQ ,or a mixture of carbonate and sulphate.

ksJalts may be used; The sulphur is reduced boiling to calcium-sulphide and is thereupon converted" by addition of alkaline salts as follows, the f V spent gas-purifying material is bu rntlime ('GaO), orquick lime quentlyfian addition is made of'alkaline fsul- Other earth-alkaline oxides; A r

or hydroxides; or similarly acting alkaline my into alkalinepolysulphides. After the con-, 7

version has been completed the formed calcium-carbonate or calcium-sulphate isprec1p1tated,,Whereupon all mpurltlessuch as are passed phides remain in solution asdoalso the alkaline ,ferro-cyanides and rhodanides, While the,

formed. ammonia will escape. a o

The lye is thereupon drainedofi andin case thesame should still contain traces of 1 tar, which may occur When using very much i polluted gas-purifyingmaterial, the lye is then boiled: with animal charcoal;

Thealkaline polysulmixture of animal charcoal and barium-sulphidelBaS), or by the introduction of sulphide lye is drained other separated from the resiof hydrogen, (H 5); "The rremaining due byyfilteringin a 'filterpress, anhydrous oxide (S0 anhydrous I (S0 or carbonic acid, (CO being introduced until the poly-sulphides are mostly i v decomposed, i. I e. until the rated. The employnientof sulphurous acid I has given the best results. v Y I i The cyanogen combinations, still contained intheglye, are'thereupon precipitatedas substantially insoluble cyanogen combinations I by means of iron' salts, suchas suspended) ferric hydrate in' neutral solution, or by earthy alkaline combinations such as chloride of calcium.

sulphuric i acid sulphur is sepa V i The remaining lye is further orked byjree peating the introduction of gas until all alka line salts are again convertedvinto alkaline I sulphates, or alkaline carbonates and until, a

is 'superfluity of gas again prevails in the soluor other basic solutions. The gases" required for decomposition can be obtained by ealcina-v tion of the spent gas-purifying material or J from the smoke-gases.

. working of the raw material is effected in one- From the aforesaid it will be clear that single operation, and that a'circuitous process is setj upjutilizing the continuous.exploitas formthe sulphur constituent maybe supplied, whether as elementary sulphur, as sul-' phurous acid, or as sulphide of hydrogen, it

"is finallyrecoveredas pure sulphur; and the e alkalinesulphates andcarbonates, (lime in form of. gypsum or chalk) are likewise recovered.' Only the lime and carbonic acids are in faetconsumed. i

- Therecovered sulphur corresponds in dual itytotriple sublimated Sicilian sulphur; it

is p erfeetlyfree from tar and ashes, is odor-1 less, tasteless, andof alively lemon-colored hue, is of extraordinary" fine distribution,

9698'degrees Chancel; When melted it has alively yellowcolor, and will notform into balls even duringprolonged storage.

I ist example Thirty parts of the spent gas-purifying material J of usual 1 composition (viz. containing approximately 32%. sulphur: and ,2% cyanogen-combinations) are. ground coarse? grained and mi-Xedwith 5 parts or burntlime and 12 parts of'waterless sulphate of sodium, (or 1 part calcined soda), and 1 placed in a steam boiler with 5 parts by Weight of water andheatedto 100C. [The heated mixture is stirred by air, blownthrough the mixture by a pump," The "mixture is boiledfor about 7 ,ing for one hour the entire sulphur; is re,

'1 whether thelye is still polluted and particu-e larly whether same still contains'tar or otheran-hour, whereupon itwill foam strongly,

and the ammonia produced therein will simultaneously be drained off., After boil du'ced to sodium-polysulphid'e solutionqand the separated calcium-carbonate and the cal cium-sulph ate deposit the impurities.

A sample is then taken in orderto ascertain coloring impurities. The sampleis mixed with sulphurous acid up to neutral re-action. The separated sulphur is filtered a'n'd dried,

- and melted at a temperature 019130 to 135 C.

' If it melts with a livelyyellow color and looks otherwise ole'anthe lye may immediately be Worked further. Ifsuch is not the case, and the'sulphur ofthe sample is brown, or it melts with a metallic gloss, thelye i's'then boiled with. animal or bone charcoal. until a sample willjyield pure sulphur. Theaddition of animal'eharcoalamounts :as aima'ximum to only 1% of the material to be worked.

The lye is filteredand anhydrous acid a terrupting thegas supply can beas'certained I calorimetrically with precision? tion of the suppliedsubstances. In whatever The separated polysulphide-sulphur is thereupon separated from the *l'iquidbyfiltrm tion, Washed ,thQIZOUghly with pure water, and dried at a temperature oiiahout 80) (1.. 7

Upon, the. introduction of anhydrous, sul

phuric acid, sulphide of hydrogen is formed which is collectedjina mixture ofburnt-lime and" sodium-sulphate, orf slacked lime. The

thus formed sodium-sulphide, (sometimes sulph hydratel can further, bevused." in the process. The lye remaining; after removal of the polysulphi die-sulphur is again treated With anhydrous" sulphuric acid" gas" until a strongsuperfluityof gas is present in the lye,

i. e. untilia-lllsodium salts are again convertedjnto sodium sul'phates. I: I I

Thev mother-lye is thenmixed' with iron salts in order to separate the cyanogen com- "binations therefrom which are; workedin known manner. The rest-oftlie lye may be used .for cooling the; sulphurrroasting-gases with the effect that as the ,colloi dal'thiosulphatejseparates from'thelye sulphur is -balled in consequence of beingheatei and isfdeposited at' the. bottom; This seoond separation of sulphur is removed from. the lye, and V he r in ng. "lye.- which-t ny; contains diam-sulphate: is agaiiir employed for the treatment: ofother materials; v p v 3 V p Thirty-- partsvof-i-groundsspent gas-purifying material of the" same: aforesaid composition are-boiledforvanfhour withE5 parts of burntglime, .wherebythe ammonia is expelled, the-:liquidiis :drawnzofi' org-filtered, and-then .phate-,-.or. sodium scarbonate Further treatmentisthe: same. as stated in the first eX- 1 The principal advantage of the treatment 7 I with lime and'alkaline sulphate, or alkalinev carbonate, lies in-the fact thatth'einsoluble calcium-carbonates separated during re ac masses Jof; gas-purifying mixed, withlQ. partsof {caleinedi sodiurnrsul U tion,

ancl' the sulphates j setarati the tar and composingthe polysulphates should not be ing the olysulphide solution with bone charcoal, be oreintroduction of theacid gas;

9. In a process as set forth in claim '7, re-

pe'ating the treatment of the solution with the 9 thiosulphate-for-rnatfion'; (Whichfmust be preinferior quality carries along the im- '10 ZPI'OCBSSgv j I from spent gaspurifyin'g materialconsisting an excess "of earthralkali oxides to bringthe ."sulphur into solutionvas-an alkali polysulbefore thejintroduction ofthe 7' T h from spent gas-purifyingmaterial consisting 4 0 7 through the solution for a finallyjseparatingtheipure sulphufrshy filtra introduced'for toQlonga-time, as otherwisea said acid gas until all the alkalineasalts 5 j 3 therein are converted intoalkaline sulphates;

vented Would takejp'lace, and sulphur, which DR. KALMAN SZOMBATHY. is separated from thiosulphate isnot only of V r purities remaining (in the lye, owing to its strong absorbing andcolloidalnature which f renders same substantially valueless in w my 1; The-process for recovering pure sulphur g inboil ng the spent material with water and phide; filtering off the solution; treating the solution with acid gas for asuflicient time to decompose the polysulphidefwithout formaand removing the sultionfof thiosulphates phur by filtration, I a a H 2 In a process as set forth in claim 1, boil- ,ing the polysulphide'solution withcharcoal;

" acid gas.

'8. In a process as set forth in claim 1', 'rep eating the treatment of the solution with the said acid gas until all the alkaline salts in the solution are converted into; alkaline sulphates.

processfor-recovering puresulphur in boilingVBO' part/shy weight of said spent material in 5 parts of; water, and 5 parts of earth-alkali oxide"; adding 12 partslof an, r

' alkaline salt to bring thesulphur into solu tionoas an" alkali polysulphide; filtering ithe solution; passing an anhydrous acid gas sufficient time to (decompose the polysulphide without formation of thio-sulphates; and removing the sul- "phuriby filtration,

, In a prooess asset ,b fthin claim 4:, hoilingthe poly sulphide solution with charcoal, ff, be'fore'introduction of the-acid gasi In a process as set forth in claim 4, mi 'peating the treatment of the solution with the said'acicl-"gas until'allthealkaline salts there-. 7 in are 'conterted into alkaline sulphates; I

' :7. Theprocessifor recovering pure sulphur fromspent gas-purifying material, consisting in boiling'the spent, material with water and an excess of an earth-alkalioxideto bring the sulphur into solution as an alkali sulphide; "adding theretoan alkali sulphatetoform an alkali polysulphide solution; filtering the I solution containing the poly'sulphide'; and 1 treating the solution withanhydrous sulfurous acidgas to-decomposethe' polysulphide Without formation: of thiosulphates; and

5 a 81111 aprocess asset fo'rthiinclaim r7, boil-, 

